Most efforts to reduce postmenopausal bone loss by nutritional means have focused on calcium, a major component of bone. Mature bone matrix also contains other components, including the trace minerals copper, manganese, and zinc. In the study described here, researchers at the University of California at San Diego investigated the effects of supplementation with these trace minerals on bone loss in older women.

At the start of this two-year, double-blind clinical trial, 113 postmenopausal women were assigned to receive calcium (1000 mg per day as calcium citrate malate), trace minerals (15 mg zinc, 2.5 mg copper, and 5.0 mg manganese daily), both supplements, or placebo. Fifty-nine women completed the study. The high drop-out rate was due, at least in part, to a high rate of gastrointestinal symptoms--probably attributable to the mannitol used as a filler in both the active and placebo tablet formulations.

At the end of the trial, subjects taking calcium plus trace minerals showed significantly less loss of bone density than those taking placebo. The group taking calcium only and the group taking trace minerals only showed bone loss changes intermediate between those of the other two groups; however, the differences were not statistically significant.

These results suggest that bone loss in calcium-supplemented women can be further decreased by increases in the intake of zinc, copper, and manganese. Additional studies in larger numbers of subjects are needed to confirm this finding.